GB1378650A - Welding - Google Patents

Abstract

1378650 Welding by pressure STERLING ELECTRONICS CORP 14 Dec 1971 58029/71 Heading B3R In a method of forming, by welding, a conductive connection between a conductor surrounded by a pressure deformable insulating material and a conductive element the insulated conductor is pressed against the element with a force sufficient to effect cold flow of the insulating material to provide an area of contact between the conductor and element, the force is reduced to a predetermined welding force value appropriate to the materials of the conductor and element and while continuing to vary the force a weld is formed, e.g. by passing a pulse of current through the contacting areas. In apparatus for stitch welding an insulated wire 116 to successive terminal pins 122 on a circuit board the wire is supplied and drawn through a central passage in an upper electrode 58 arranged for cyclic movement towards and away from a stationary lower electrode 40. A carrier slide 36 supports the upper electrode 58 and is driven in vertical cyclic motion by a drive slide 38, a spring 51 forming the drive connection between the drive and carrier slides 38, 36 during the operative portion of each cycle. Switches are provided to ensure that the welding current' pulse is only applied when the drive slide 38 is moving upwardly i.e. when the pressure applied to the conductor wire by the upper electrode is decreasing. Power driven cam means are connected to the drive slide 38 by a drive rod 44, a spring 75 ensuring the return movement of the drive slide to its upper, rest position. A guide ring may be provided (Fig. 7, not shown) to keep the wire close to the circuit board as it is drawn between the welded connections and shearing blades to sever the wire upon completion of a network.